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EAGE/SEG Summer Research Workshop - Processing and imaging of seismic data
- Conference date: 31 Aug 2003 - 04 Sep 2003
- Location: Trieste, Italy
- ISBN: 978-94-6282-115-6
- Published: 31 August 2003
40 results
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The Data-Driven Seismic Value Chain
More LessCross-disciplinary communication between specialized E&P projects should be facilitated by a conceptual framework that can be used at different levels of abstraction. In this framework an unbiased strategy need be followed, meaning that parameterization of the subsurface model must be delayed as much as possible. One consequence of delayed parameterization is that velocity models should not drive the seismic processing algorithms.
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Stacking Velocities for Different Offsets in the Medium with Laterally Inhomogeneous Layer
Authors E. Blias and S. GritsenkoIn this paper, we consider the behaviour of stacking velocities, depending on the NMO offsets. For small offsets, stacking velocity can be expressed in terms of the second-order derivative of the moveout function.
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New Traveltime Approximations for a Layered Transversely Isotropic Medium
More LessThe basic idea of this paper is to derive approximate equations for vertical slowness for P and SV waves and PP, SS and PS traveltimes in TIV media not using a weak-anisotropy approximation.
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Data-Driven Imaging with Second-Order Traveltime Approximations
More LessStarting with the general concept of second-order traveltime approximations for seismic reflection imaging, we discuss the number of free parameters, i.e., spatial derivatives of the traveltime, for different acquisition geometries and processing approaches ranging from the most general multi-parameter problem down to the well-known single-parameter approach used in the common-midpoint stack.
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Finite-Offset CRS Attributes for Imaging and Inversion
Authors S. Bergler and P. HubralStarting with the concept of the surface-to-surface propagator matrix, we explain how the elements of the matrix are related to kinematic wavefield attributes.
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3D Zero-Offset CRS Stack for Narrow-Azimuth Data - Formulation and Examples
Authors G. Cardone, A. Christini, E. Bonomi, P. Marchetti, R. Zambonini, P. Hubral and J. MannThe common-reflection-surface (CRS) stack is a macro-model independent seismic reflection imaging method that has proved to accurately detect and characterise meaningful events in the pre-stack data. As any 3D data-driven method, it requires an azimuthal distribution of traces as uniform as possible, in order to properly infer necessary information from the data. Its application to 3D datasets with narrow-azimuth acquisitions requires some simplified assumptions of the underlying theory. We present an approximated formulation and a related processing method that still represents an improvement with respect to conventional techniques currently employed. The advantages of the method when performing stacking velocity analysis are demonstrated on a synthetic example
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CRS Imaging of Complex Geology in 2D/3D Seismic Data
Authors H. Trappe, R. Coman, G. Gierse and J. PruessmannThe Common-Reflection-Surface (CRS) stacking technique provides a powerful time domain imaging especially in case of complex geology data with low signal-to-noise ratio. The macro-model approach does on principle save the effort to produce a macro-model. However, the method allows as well the input of a velocity model as a guide function, which is automatically improved. A coarse initial velocity model is helpful especially in case of strong multiple wavefields.
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Data-Driven Meets Model-Driven - 3D-CFP Operator Updating
Authors M. J. van de Rijzen, D. J. Verschuur and A. GisolfIn this paper an iterative procedure will be presented that allows us to create 3D CFP-gathers and update 3D CFP-operators in case of a sparsly sampled acquisition geometry. The procedure is applied to a synthetic dataset and shows satisfactory results.
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Data-Driven Meets Model-Driven - An Approach to 3D CFP-Redatuming
Authors S. Tegtmeier, D. J. Verschuur and A. GisolfWavefield redatuming can be very efficient to overcome the overburden imprint on the target area. Due to an increasing amount of 3D data it becomes more and more important to develop a feasible method for the redatuming of 3D prestack data. We propose an approach that can be used in general for wave-equation datuming and present a strategy to perform CFP-redatuming of sparse 3D data using this approach. Two tests applying the modified redatuming approach to synthetic 2D data show satisfying results implying, that this method, indeed, can be used for the redatuming of sparse 3D data.
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CFP Subset CRS, CRS Subset CFP or CFP + CRS?
More LessThe Common Focal Point (CFP) method and the Common Reflection Surface (CRS) stack method are compared. The CRS method is a fast, highly automated procedure that provides high S/N ratio Migration to Zero Offset (MZO) images, by combining per image-point the reflection energy of a tangent are segment to the reflector.
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Full Prestack Redatuming without the Velocity-Depth Model - Is It Practical?
Authors K. Erickson, R. Burnstad, P. G. Kelamis and D. J. VerschuurIn land environment, the proper definition of a complex near-surface is probably one of the most challenging and controversial issues. Attempts to attack this problem range from conventional statics, to the more sophisticated tomography and wave equation-based redatuming algorithms.
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Automatic Imaging - A Practical Reality
Authors K. Stinson, W. K. Chan, E. Crase, M. Reshef, A. Webster and M. RothA system for automatic, high density migration velocity estimation and imaging has been developed. Imaging velocities are calculated at every CMP and time location, and are iteratively updated to achieve optimal image quality. 2D and 3D real and synthetic examples are presented, with best previous human results pitted against the automatic computer images
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Tomographic Velocity Model Estimation with CRS Attributes
By E. DuveneckThe Common-Reflection-Surface (CRS) Stack can be used to extract kinematic information for the construction of velocity models from seismic prestack data.
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Velocity Estimation by CRS Method - A GPR Real Data Example
Authors H. Perroud and M. TygelIn this presentation, we describe the use of the Common Reflection Surface (CRS) method to estimate velocities from Ground Penetrating Radar (GPR) data.
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Tomographic Inversion of Focusing Operators - The Conversion from Data to Model in a Data-Driven Way
Authors B. E. Cox and D. J. VerschuurBy means of the Common Focal Point (CFP) technology [1, 2], seismic two way traveltime data can be converted to one way focusing operators. These focusing operators are generally used for model independent imaging, so that the image will not be constrained by any (user-defined) model. Nevertheless, when a velocity model of the subsurface is requested, it can be obtained from these focusing operators by tomographic inversion. This abstract presents a method for the inversion of focusing operators using data-driven model parameterization. It is demonstrated that this inversion results in an accurate unconstrained estimation of both velocities and focal point locations.
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Differential Time Shifts in the Radon Domain for Estimation of Elastic Parameters in a VTI Medium
Authors R. J. Ferguson and M. K. SenA method is presented for estimating VTI parameters in locally homogeneous media. Focusing operators and CFP gathers are computed using the best values of VTI parameters available (from moveout analysis or other techniques).
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Velocity Analysis Based on Prestack TAU Migration
More LessPrestack migration velocity analysis in the vertical time domain reduces the velocity-depth ambiguity usually hampering the performance of prestack depth-migration velocity analysis.
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Migration Velocity Analysis by Depth Image-Wave Remigration - First Results
Authors J. Schleicher, A. Novais and F. P. MuneratoThe image wave equation for depth remigration is a partial differential equation that is similar to the acoustic wave equation.
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Consistent Velocity Model Building - Matching Model to Migration
Authors W. E. A. Rietveld, J. Etgen and F. BilletteRecent advances in imaging and computing technology have made prestack wave-equation depth migration feasible in a production environment. However, the state-of-the-art in velocity model building is still based on mainly Kirchhoff prestack depth migration and raybased tomographic inversion. This mismatch between migration algorithm and velocity model will ultimately limit the final image quality. This paper discusses some of the issues around the mismatch of velocity model building and migration tools and other issues that hamper the derivation of an optimal migration velocity model.
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Migration Velocity Analysis by Recursive Wavefield Extrapolation
Authors P. C. Sava and B. BiondiWe present a wave-equation method of migration velocity analysis, based on the linear relation that can be established between a perturbation in the migrated image and the corresponding perturbation in the slowness function
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Velocity Updating from Wavefield-Continuation Migration
Authors B. Biondi, R. G. Clapp and W. SymesWith wavefield-continuation migration methods being used routinely for imaging project in complex areas, the ability to perform Migration Velocity Analysis (MvA) starting from the results of wavefieldcontinuation migration is becorning essential to advanced seismic imaging.
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Building High-Resolution Velocity Models in the Gulf of Mexico with Wave-Equation Depth Migration
Authors A. M. Popovici, S. Crawley, M. Fliedner, D. Bevc, W. Ritchie, K. Stewart, A. Lau and C. YinThe deepwater Gulf of Mexico sub-salt regime has been a major focus of attention as 3-D pre-stack depth migration (PSDM) solutions have come of age.
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Seismic Imaging of Superficial Structures by Traveltime and Wavefield Tomographies
Authors J. Virieux, S. Operto, A. Herrero, C. Ravaut, L. Improta and P. Dell‘AversanaExtracting information about the subsurface velocity from multi-offset data may require a two-fold strategy because the acquisition is sensitive to two different characteristic wavelengths of the velocity structure. The initial step is the reconstruction of the smooth part of the velocity structure by using first-arrival time tomography in contrast with the classical velocity analysis requiring strong subhorizontal interface contrasts
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Simultaneous Inversion for Multiples and Primaries
Authors Y. Luo, P. G. Kelamis and Y. WangThis paper presents a new method to estimate primary reflections through inversion instead of conventional least-squares adaptive-subtraction.
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Multiple Attenuation after Migration
Authors P. C. Sava and A. GuittonMultiples can be suppressed in the angle-domain image space after migration. Primaries and multiples have different angle-domain moveout, therefore they can be separated using techniques similar to the ones employed in the data space prior to migration. We use Radon transforms in the image space to discriminate between primaries and multiples. This method has the advantage of working with 3-D data and complex geology. It offers an alternative to the more expensive Delft approach.
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Refined Depth Imaging Based on Flexible Finite-Offset Tomography
Authors P. Guillaume, F. Audebert and X. ZhangThe purpose of imaging is 1) to focus the seismic data, 2) to position all seismic events correctly in space and 3) correct for amplitude and illumination effects.
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High Resolution Tomographic MVA with Automation
More LessPrestack reflection tomography is gradually being promoted from a method adjunct to the vertical velocity updating scheme, to become the main model building tool, used routinely on all imaging projects.
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Stereotomography - A Fast Approach for Velocity Macro-Model Estimation
Authors M. Alerini, G. Lambaré, R. Baina and P. PodvinStereotomography is a method for estimating velocity macro-model from seismic reflection data. It relies on the concept of locally coherent events, allowing for a much easier picking than in classical travel time tomography.
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A Practical Approach to Automated PP Angle Tomography
Authors S. -K. Foss, B. Ursin and A. SollidThe use of the differential semblance misfit function on common image point gathers in the angle domain, lends itself to an automated tomographic approach through a gradient based search of the model space. The common image point gathers are created by the AVA-corrected or incomplete generalized Radon transform. We present a real data example of PP scattering events and an approach to regularize the optimization by respecting geological features.
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Flexible B-Spline Model Parameterization Designed for Reflection Tomography
Authors T. Perdrizet and D. SinoquetReflection tomography is an efficient method to determine a subsurface velocity model that best fits the traveltime data associated to the main events picked on the seismic sections. A careful choice of the model representation has to be done: a blocky model representation based on regular gridded b-spline functions has been proposed.
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Stereotomography - Extension and Application to Converted Waves
Authors M. Alerini, G. Lambaré and S. Le BégatPicking of the information in prestack data cube is certainly one of the most difficult tasks in velocity estimation methods. This difficulty is enhanced when dealing with converted waves since PP and PS events have usually to be paired in order to obtain two cinematically consistent velocity models.
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Velocity Macro Models
More LessVarious aspects of macro models are briefly mentioned, with emphasis on their relation to geological structures and on their role in inversion of seismic data.
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Direct Arrivals Stereotomography - 2D Walk-Away Synthetic and Real Data Applications
Authors A. Gosselet, S. Le Bégat and S. PetersenNew developments in seismic data integration ask more and more for tomographic inversion method able to handle data from alternative acquisition geometries.
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Velocity Estimation in Complex Chalk
Authors M. Sugrue, I. F. Jones, E. J. Evans, S. Fairhead and G. MarsdenThe theme of the 2003 imaging workshop concerns the contrast between different. philosophies of 'model building': whether an explicit, user detemined model should be imposed throughout the processing, with user updates at each step; or alternatively, whether user intervention should be kept to a minimum so as to avoid preconceived bias, and instead to allow the data itself to guide some heuristic process to converge to an optimal solution.
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Optimal Velocity Models for Wavefield Continuation Migration
Authors D. Bevc, M. M. Fliedner, A. M. Popovici and B. BiondiFor optimal imaging results, velocity model updates must be based on image gathers derived from the same migration engine that is used in the final imaging.
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Interpretive Migration Velocity Analysis with Applications to GPR
Authors M. Pipan, E. Forte, G. Dal Moro, P. Gabrielli and I. FinettiVelocity model refinement by a combination of Deregowsky and focusing techniques is an effective solution to image complex shallow subsurface conditions by means of GPR. Including geological knowledge in the velocity analysis of CRP gather considerably reduces costs and uncertainties of the final velocity model and allows rapid convergence to the correct solution. Applications to high resolution GPR study of alluvial sediments confirm the accuracy of the results attainable by PSDM in imaging complex sedimentological patterns.
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Travel-Time Inversion in Shell - Towards High-Resolution Geologically Plausible Velocity Models
Over the years, travel-time inversion (TTI) has established itself within Shell as the preferred method to construct 3-D velocity models in depth for subsequent imaging purposes. Vast experience has been built up with layer based TTI and more recently its use in gridded or hybrid models has taken off. TT1 in gridded and hybrid models has been developed for geologies for which a layer-based description is less appropriate. In this presentation we present a number of case studies demonstrating the value of TII.
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